The following relates generally to wireless communication and more specifically to beam refinement for active and candidate beams.
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system). A wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
Wireless communication systems may operate in millimeter wave (mmW) frequency ranges, e.g., 28 GHz, 40 GHz, 60 GHz, etc. Wireless communications at these frequencies may be associated with increased signal attenuation (e.g., path loss), which may be influenced by various factors, such as temperature, barometric pressure, diffraction, etc. As a result, signal processing techniques, such as beamforming, may be used to coherently combine energy and overcome the path losses at these frequencies. Due to the increased amount of path loss in mmW communication systems, transmissions from the base station and/or the UE may be beamformed.
Wireless communications between two wireless nodes, e.g., between a base station and a UE, may use beams or beam-formed signals for transmission and/or reception. A beam used for such wireless communications may be referred to as an active beam or a serving beam. Sometimes, due to changing communication conditions, movement of a UE, etc., an active beam may be refined. For example, a UE active beam or a base station active beam may be refined. Additionally, there may also be a need to explore candidate beams or alternatives to the currently employed active beam and/or to measure a beam state of the active beam as well as other beam candidates. Thus, the active beam may initially be picked from a reference beam and then refined over time.